Bohr Model of the Atom — Interactive NEET Chemistry Visual Lab
The Bohr model pictures the atom as a dense nucleus of protons and neutrons orbited by electrons in fixed energy shells. Shown here is sodium (Na, Z = 11): 11 protons and 12 neutrons in the nucleus, with 11 electrons arranged 2, 8, 1 across the K, L and M shells. Tap any part of the interactive model below to explore it, in plain English and with an exam-accurate NEET note.
Explore the Bohr model of the atom — tap any part
Tap a structure to see what it does in plain English plus an exam-accurate NEET note, or hit Guided tour to be walked through it step by step.
Bohr Atom
Atomic structure
Selected structure
Bohr Atom
The Bohr model pictures the atom as a tiny, dense nucleus of protons and neutrons, orbited by electrons in fixed shells. Shown here is sodium (Na): 11 protons and 12 neutrons in the nucleus, with 11 electrons arranged 2, 8, 1 across the K, L and M shells. Tap any part, or take the guided tour.
NEET note
▸ All structures & functions
- Nucleus
- The tiny, dense core at the centre holding almost all the atom's mass and its positive charge.
- NEET:Nucleus: contains the protons and neutrons (nucleons); carries the atom's entire positive charge and ~99.9% of its mass.
- Protons
- Positively charged particles packed in the nucleus — their number decides which element it is.
- NEET:Protons (+1 each): 11 in sodium. The atomic number Z = number of protons = 11.
- Neutrons
- Neutral particles in the nucleus that add mass but no charge.
- NEET:Neutrons (no charge): 12 in this Na-23 atom. Mass number A = protons + neutrons = 11 + 12 = 23.
- Electrons
- Negatively charged particles that occupy permitted, fixed energy levels (shells) around the nucleus.
- NEET:In Bohr's model, electrons occupy permitted stationary orbits (shells) of definite energy. Each carries −1 charge; sodium's 11 electrons fill them as 2, 8, 1 (K, L, M).
- K Shell (n=1)
- The innermost orbit, closest to the nucleus — it fills first and holds up to 2 electrons.
- NEET:K shell (n = 1): maximum 2 electrons (2n² = 2); lowest energy, filled first.
- L Shell (n=2)
- The second orbit out — it holds up to 8 electrons and is completely full in sodium.
- NEET:L shell (n = 2): maximum 8 electrons (2n² = 8); fully filled in sodium.
- M Shell (n=3)
- The third orbit — in sodium it carries just one electron.
- NEET:M shell (n = 3): holds sodium's single outermost electron; capacity 18 (2n²) but only 1 is present here.
- Valence Electron
- The lone outer-shell electron — the one sodium easily loses to become a positive ion.
- NEET:Valence electron: sodium's single M-shell electron, readily lost to form Na⁺ with electrovalency +1, which accounts for sodium's high reactivity.
Bohr Atom: structures & functions
A quick, exam-focused reference for every structure in the Bohr model of the atom — each with a plain-English answer and the precise NEET point.
What is the nucleus of an atom?
The tiny, dense core at the centre holding almost all the atom's mass and its positive charge. Nucleus: contains the protons and neutrons (nucleons); carries the atom's entire positive charge and ~99.9% of its mass.
What are protons?
Positively charged particles packed in the nucleus — their number decides which element it is. Protons (+1 each): 11 in sodium. The atomic number Z = number of protons = 11.
What are neutrons?
Neutral particles in the nucleus that add mass but no charge. Neutrons (no charge): 12 in this Na-23 atom. Mass number A = protons + neutrons = 11 + 12 = 23.
What are electrons?
Negatively charged particles that occupy permitted, fixed energy levels (shells) around the nucleus. In Bohr's model, electrons occupy permitted stationary orbits (shells) of definite energy. Each carries −1 charge; sodium's 11 electrons fill them as 2, 8, 1 (K, L, M).
What is the K shell?
The innermost orbit, closest to the nucleus — it fills first and holds up to 2 electrons. K shell (n = 1): maximum 2 electrons (2n² = 2); lowest energy, filled first.
What is the L shell?
The second orbit out — it holds up to 8 electrons and is completely full in sodium. L shell (n = 2): maximum 8 electrons (2n² = 8); fully filled in sodium.
What is the M shell?
The third orbit — in sodium it carries just one electron. M shell (n = 3): holds sodium's single outermost electron; capacity 18 (2n²) but only 1 is present here.
What is the valence electron in sodium?
The lone outer-shell electron — the one sodium easily loses to become a positive ion. Valence electron: sodium's single M-shell electron, readily lost to form Na⁺ with electrovalency +1, which accounts for sodium's high reactivity.
Frequently asked questions
What is the nucleus of an atom?
The tiny, dense core at the centre holding almost all the atom's mass and its positive charge. Nucleus: contains the protons and neutrons (nucleons); carries the atom's entire positive charge and ~99.9% of its mass.
What are protons?
Positively charged particles packed in the nucleus — their number decides which element it is. Protons (+1 each): 11 in sodium. The atomic number Z = number of protons = 11.
What are neutrons?
Neutral particles in the nucleus that add mass but no charge. Neutrons (no charge): 12 in this Na-23 atom. Mass number A = protons + neutrons = 11 + 12 = 23.
What are electrons?
Negatively charged particles that occupy permitted, fixed energy levels (shells) around the nucleus. In Bohr's model, electrons occupy permitted stationary orbits (shells) of definite energy. Each carries −1 charge; sodium's 11 electrons fill them as 2, 8, 1 (K, L, M).
What is the K shell?
The innermost orbit, closest to the nucleus — it fills first and holds up to 2 electrons. K shell (n = 1): maximum 2 electrons (2n² = 2); lowest energy, filled first.
What is the L shell?
The second orbit out — it holds up to 8 electrons and is completely full in sodium. L shell (n = 2): maximum 8 electrons (2n² = 8); fully filled in sodium.
What is the M shell?
The third orbit — in sodium it carries just one electron. M shell (n = 3): holds sodium's single outermost electron; capacity 18 (2n²) but only 1 is present here.
What is the valence electron in sodium?
The lone outer-shell electron — the one sodium easily loses to become a positive ion. Valence electron: sodium's single M-shell electron, readily lost to form Na⁺ with electrovalency +1, which accounts for sodium's high reactivity.
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